In recent years, a radio system which transmits information via radio communication is used in various situations. The radio system includes, for example, a cellular system, a satellite broadcasting system, a wireless local area network (LAN) system, a TV broadcasting system, a radio broadcasting system, or the like. There is a case where, in such radio systems, in the case where frequency bands utilized overlap with each other, radio transmission interferes with each other. It is therefore desire to provide a technology for avoiding interference among different radio systems.
For example, the following Patent Literature 1 discloses a technology of avoiding a primary system from being fatally interfered in the case where there are a plurality of secondary systems upon secondary utilization of a frequency band.